Each U.S. airline sets its own policies about what it will and won’t do for delayed passengers, with no federal requirements. Only when you are involuntarily bumped from a flight must you be paid compensation. Even then, under federal law, if an airline can get you to your destination within one hour, you get nothing. Between one and two hours, the airline must pay an amount equal to your one-way fare, $200 maximum. More than two hours late (or four hours internationally) and it’s 200% of your fare, $400 max. In all cases, you can keep your original ticket for credit on a future flight. But if the airline substitutes a smaller aircraft or you’re flying on a plane with fewer than 60 seats, then the airline owes you zilch.

Lost baggage is another story. There’s a $3,000 ceiling on reimbursement for delayed, lost, or damaged bags. On international round-trips that originate in the U.S., it’s about $1,375 (tied to the exchange rate of the dollar against other currencies).

European air travel is a bit more customer-friendly. Passengers facing long delays or cancelled flights (even by bad weather) or who get bumped are entitled to hefty pay-outs when flying European Union member airlines (like Air France or Alitalia) within Europe or into Europe from foreign countries (apr.europa.eu). Passenger-protection rules call for payment up to $795--depending on the flight’s distance--plus a full refund or alternative flight, meal vouchers, free phone calls or e-mails, and even lodging if an overnight stay is necessary.

On our side of the pond, the Feds are finally stepping into the fray. A Passenger Bill of Rights (www.flyersrights.com), which would mandate steps airlines must take for lengthy ground delays, is making its way through Congress. And in July, the Department of Transportation sought public comment on proposed rule changes that could raise payments to as much as $1,248 for bumped flyers.

In the meantime, take steps to ensure you get your due. Check in early. Last to check in is first to be involuntarily bumped. If problems arise, complain immediately so that those on the scene can document and respond. If you’re lucky, the clerk might book you on another airline with the next flight out, or at least offer meal or hotel vouchers. Be firm but insistent. Don’t let the agent move on to the next customer until resolving your problem. And create a paper trail. Take notes. Have service reps write you a receipt. If your case is delayed, you’ll want backup at the ready. The DOT Web site (http://airconsumer.ost.dot/gov) has links to airline customer-service plans.